Coupler Grating Parasitic Radiation Management
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Solution Overview
Problem
Flood illumination in photonic integrated circuits leads to parasitic radiation, causing interference and reducing the performance of photonic integrated devices due to the reflection of radiation outside the coupling region, which is not effectively addressed by existing solutions like additional processing steps or reflective gold films.
Innovation Solution
A photonics integrated device with a coupler grating and a grating for blocking, reflecting, or redirecting radiation away from the coupler grating, positioned to prevent parasitic radiation from interfering with the coupler grating, allowing for efficient coupling of radiation while minimizing parasitic reflections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If flood illumination is used to relax alignment requirements, then alignment tolerance is improved, but parasitic radiation increases causing interference and performance deterioration
Solution Approach 1:
The device surface is segmented into a coupling region with the coupler grating and a non-coupling region with the reflective grating. This segmentation allows flood illumination to be used for its alignment tolerance benefits while the reflective grating confines parasitic radiation to its own segment, preventing it from interfering with the coupling region
Solution Approach 2:
The harmful parasitic radiation is extracted and redirected by the reflective grating away from the coupling region. The reflective grating specifically targets and removes parasitic radiation paths that would otherwise interfere with the coupler grating, isolating the harmful effects to a controlled region
2Object-affected harmful factors
If a reflective gold film is added to reduce parasitic radiation, then parasitic radiation is reduced, but device complexity and manufacturing cost increase
Solution Approach 1:
The reflective grating is merged with the coupler grating into a single integrated device structure. Both gratings are formed in the same waveguide layer using the same lithographic process, eliminating the need for separate gold film deposition and additional processing steps. The two gratings work together in the same physical space to achieve both coupling and parasitic radiation reduction
Solution Approach 2:
The reflective grating serves a dual function: it acts as a diffraction grating for its specific wavelength range while simultaneously serving as a reflective element to redirect parasitic radiation. This self-service approach eliminates the need for separate reflective gold films, as the grating structure itself provides both coupling and parasitic radiation management functions
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution significantly reduces parasitic radiation interference, enhancing the noise performance and alignment tolerance of photonic integrated devices, enabling robust operation against positional variations and vibrations, and allowing for simultaneous excitation of multiple grating couplers for improved multiplexing.
Implementation Method 1
a grating for blocking, reflecting or redirecting radiation away from the coupler grating... prevent at least some radiation from said flood illumination, impinging at the grating for blocking, reflecting or redirecting radiation away from the coupler grating and thus impinging at a position away from the coupler grating, from being reflected within the device towards the coupler grating
Implementation Method 2
a coupler grating at the surface of the device for coupling radiation from said flood illumination towards the integrated waveguide
Data Source
Figure 1a~1b
Figure 2~4
Figure 5~7
AI summary
A photonics integrated device (100) for coupling radiation using flood illumination is disclosed. The photonic integrated device comprises an integrated waveguide (113), a coupler grating (104) at the surface of the device (100) for coupling radiation from said flood illumination towards the integrated waveguide (113), and a grating for blocking, reflecting or redirecting radiation away from the coupler grating (103) at the surface of the device (100). The grating for blocking, reflecting or redirecting radiation away from the coupler grating (103) thereby is positioned relative to the coupler grating (104) so as to prevent at least some radiation from said flood illumination, impinging at the grating for blocking, reflecting or redirecting radiation away from the coupler grating and thus impinging at a position of said surface away from the coupling grating, from being reflected within the device (100) towards the coupler grating (104).